Tool for securing small metal screws in threaded position



ITION April 1935- F. A. STEVENS TOOL FOR SECURING SMALL METAL SCREWS INTHREADED POS Filed Aug. 10, 1934 mid/f 55606776 y MW Patented Apr. 7,1936 2,036,553

UNITED STATES PATENT OFFICE TOOL FOR SECURING SMALL METAL SCREWS INTHREADED POSITION Frederick A. Stevens, Providence, R. I. ApplicationAugust 10, 1934, Serial No. 739,290

' 3 Claims. (01. 813.6)

The present invention relates to tools, and These fittings must beadjusted accurately to m p r i ul r y to ools f r securing small conformto the facial and visual requirements 'metal screws in threadedposition. of each case; and when once fitted, it is highly Parts Of Op cm n g nd other deimportant that the lenses shall remain in the 5 vicesthat are similarly heldtogether, have a prescribed positions. As thescrews I! have a 5 en to para ecause the screws do no tendency toloosen, particularly because of the hold tight. According to theinventions disclosed strains encountered by flexing the temples and inapplications Serial No. 683,323, flied August wiping the glasses,vibrations due to V 1933. Serial No. 722.092, filed April 24, 19 4, and.the like, itis impossible toobtain this desired l0 and Serial No.732,786, filed June 28, 1934, minute, result; for to maintain the lensesin the 'prethreaded, light, metal parts, having very few scribedposition, it is necessary that the screws threads, such as is the casewith the screws and I! shall continue to hold the assembled parts dowelsused in the manufacture and maintenance firmly t ether, with utloosening,

' oi ophthalmic mountings and similar articles, These screws I2 havevery short, threaded are assembled and locked in position in a v yportions; say, about four or five threads long, 15

efl'ective manner. or about ninety to the inch. The depth of the A chiefbj c f th nv ntion is to provide a hereinafter mentioned aperture 42 isin the novel tool for producing; a uniform locking fneighborhood o1thirty thousandths or an inch. feet for screws and the like of theabove-described The diameter of these screws is only about fortycharacter. flve thousandths of an inch, so that the diameter 20 Otherand further objects of the invention of th aperture 4: may be abouttwenty t will be explained hereinafter, and will be more ath of an inchI particularly pointed out in the appended claims." T inut size of thescrews I: used in these The invention will be described in connectionophthalmic mountings i a i ortant factor with e a mp nying drawing, inwhich Fi 1 to be considered. The smallness of the screw 26 is anelevation of a novel tool embodying h diameter, the shortness of thethreaded portion, present invention in its preferred form; Fig. 2 a dthe speed at which the screws I: are proi a corre p n ing pl n; Fig. 3is an enlarg duced, resultingin variations from cylindrical s t upon thei e H o Fi 2. shape, as hereinafter explained, all play their 30 lookingin the direction of the arrows, and showrole in reducing the permanencyoi the holding 30 in the tool in use; Figs. 4 and 5 are sections powerthat. may be expected or these minute, taken p n the lines H and 5-4,'respecthreaded members. While the defects are of ive y. 01 iglooking nthe direction the such a nature as tobe visible only under magniarrows;Fig. 6 is a, view imilar o flcation, so that it becomes necessary, forillusmodification; Fig.7 is seetlon'teken up e trative purposes, toexaggerate the drawing, 35 line 1--'! 01' Fig. 6, looking in thdirection 0! theyare nevertheless the prime causes of the said thearrows; Fig. 8 is a view of a further modiloosening. I i fl flt ni andFi 9' is an enlarged section illus- According to the inventionsdisclosed in the 1 r 1 8 the action of the tool upon the screw,above-designated applications, the diiliculties at- 40 as illustra edupon a mall r al n Fi tendant upon such loosened screws are overcomeErrors of human vision may be corrected by by providing the screw II, atits threaded end,- p pe y Prescribed lenses, mounted in fi i with 9.preferably cylindrical aperture 42 that m stly of me al. and held therby ve y small extends centrally along, or parallel to, the axis, screws.One of th se fittings s shown s a or longitudinally of the screw l2. Acontinuous,

iens-holding metal rim 2 of a pair of spectacles, annular, ezteriorlythreaded wall 44 is thus 45 having metal en Pieces 4 and 6 between whichformed about the aperture 42. Preferably, the

, swings a temple 8 upon a. dowel (not shown). length of th aperture 42i about the same a The end pieces 4 and 6 are usually held together thelength along which the screw threads extend,

by one 01 the said very small screws, shown as and the aperture islocated in the neighborhood an externally threaded, cylindrical, metalscrew of thesescrew threads, as shown.

I2 disposed loosely in a cylindrical opening H The operation isexceedingly simple and most.

or the end piece 8 and" threaded into an intereffective. With the partsassembled, and the nally threaded, cylindrical opening l8 in thethreaded members threaded together, as shown,

end piece 4. The head l8 of the screw II-is for example, in Fig. 3, ajaw 82 is positioned seated in a countersink 20 '01 the end piece 8..againstthe head ll of the screw l2, and the swag- 55 ing mandrel 48 isnow driven into the aperture 42. A force is thus exerted against theannular wall 44 of the aperture 42, toward the supporting jaw 82,resulting in expanding the continuous, annular wall 44 preferably in alldirections radially outward from the axis of the screw I2, but withoutbreaking the continuity" of the annular wall 44. The annular wall44lit-hus becomes swaged into tight engagement with the wall of thethreaded, cylindrical 'opening IE to :cause the exterior threads of thescrew l2, throughout substantially the said length along which the screwthreads extend, to lock frictionally against the interior threads of theopening it. As the continuity of the annular wall is not broken, theexternal threads of the annular wall remain tight, frictional engagementwith the internal threads of the walls of the opening It, by reason ofthe in herent resiliency of the metal of which the' screw I2 is made,without splitting the annular wall and without ,relying upon outside,supplementary were of substantial length,this would not be seri- .theremaining thread convolutions.

holding-member aids, such as a locking plug, to held the annular wallin'place. The mandrel 46 maybe withdrawn and the aperture 4'2 leftentirely empty, yet a very effective, non-loosening joint is thusprovided, that requires considerable force to produce-the integral,circular expansion, and that resists compression and consequentloosening to a remarkable degree.

The mandrel may be circular in cross section, as described in the saidapplication, .Serial No. 722,092; .er oval, or triangular, or square, orit may have any other irregular shape, as described in thesaidapplication Serial No. 732,786; In all cases, however, the free endof the mandrel is of cross sectionsmall enough to permit the mandrel toenter the aperture 42-, but the body oiv the mandrel is large enough toenable the mandrel, during its entry into the aperture 42, to effect theradial expansion before described, without breaking the continuity ofthe annular wall 44.

The screws l2 and the like that are employed in ophthalmic mountings areof such very small dimension, as indicated above, that they present veryweak resistive forcesto the aetion of the tools that cut the threadsthereon. The resistive force is particularly weak at the extreme, freeend 60 of the screw l2, and increases with. the distance from the saidfree end 6|! inward toward the screw head l2. The said thread-cuttingtools consequently-act to reduce the diameter of thevscrew l2 more atthe said free end 68 than along the body thereof, producing a more orless tapering eflect inthese members near the free end 60. Thisreduction in diameter near the free end 60 is particularly noticeable atthe tops of the threads.

If the mandrel were cylindrical, therefore, and if the apertures 42 werealso cylindrical, the mandrel would expand the thread convolutionsnearthe said free end .60 against the threaded wall of the opening itwith less pressure than Not only that, but the degree of pressure withwhich the said threadconvolutlons near the said free end 60 bear uponthe wall of the opening it would be successively less and less in thedirection toward the freeend E9 of the screw l2. If the screw l2 ous,for the remaining thread convolutions could be relied upon to hold theparts effectively together. Such considerations do not apply, however,.where the screw-thread convolutions are so few in number that everythread convolutionmust be relied 'upon to carry its share of the holdin:power required hold the parts together.

rom the said free end 60 toward the head I8 of the screw l2. Thiscompensating effect is produced by using a tapering mandrel 46, thesmall end of the taper being at the free end of the mandrel, asillustrated. When a mandrel of this shape is driven heme, as illustratedin Figs. 3 and 9, the thread convolutions of the screw l2 will all beexpanded against the wall of the threaded opening l6 so as to bearthereagainst with approximately uniform holding action. If anything,

indeed, the holding action of the thread convolutions near the free end60 of the'screw l2 will be greater than that of the threads fartheraway.v

The use of a tapered mandrel 46, furthermore, makes it possible toemploy a shorter aperture 42 than would be required with a cylindricalmandrel; but cylindrical mandrels may also be embodied in the tool ofthe present invention.

The depth and diameter of the aperture 42- v should be suchas willproduce the desired radial expansion for the particular purpose in hand.

The threaded, metal, annular wall 44 must possess strength andflexibility to withstand the expanding operation without fracture. Theflexibility must be of such a nature as to allow, in case of need, as toreplace a broken lens, withdrawal of the screw l2 intact, at reinsertionof the same screw 52 or another screw l2, and a relocking, ii desired;for the locking of the screw does not injure either the screw l2 itself,or the parts in which it is locked. The manner of application andcontrol of this internal-expansion principle, as applied to varyingshapes, sizes and conditions, and by theprogressive use of the saidtool, has

resulted in a locking achievement not heretofore produced.

The compensating mandrel 4B, intended for the entrance andexpansion ofthe aperture 42, may

be mounted on one jaw 18 of a hand teol 80; and the cooperatingsupporting anvil 82 for the head I8 of the screw on the other jaw 84,the mandrel.

46 and the anvil 82 being in alinement when the tool is elfective, asillustrated in Figs. 3 and 9. The head l8 of the screw I2 is engaged bythe anvil 82, as before described, and the mandrel 46 is driven homeinto the aperture 42 by progressively pivoting the jaws 18 and 84toward'each the tool will efi ect withdrawal of the mandrel 45.

By varying the degree of pressure applied by a put.

the hand to the handles 88 and 90 of the hand tool 88, when a taperingmandrel is employed, or by varying the diameter of a cylindricalmandrel, it is possible to obtain practically any desired degree ofuniform, frictional engagement, de-- pending upon the use to which thejoint is to be The more nearly cylindrical the screwthreaded member I2is, the less will be the range of expansion of the wall 44 that may berequired.

The contacting end of the'supporting anvil 92 is shown slightlysmaller'in diameter than the diameter of the screw head I9 against whichit functions. This ensures that the head- I9 shall, at all times,contact with the anvil 92 when the mandrel 46 is engaged in itsexpansion of the walls of the aperture 42. The double contact thusproduced at opposite ends of the screw I2 ensures a completelycontrolled, radial expansion. To obtain such a controlled, even, radi'alexpansion, it is desirable that the pressure should be applied to marked9I in Fig. 9. The downward drive of the both ends of the screw I2 at oneand the same time, else there might be an endwise crowding of the screwagainst the threads of theopening I9, instead of the desired expansion.r

If, for example, the countersink 29 were deeper than the thickness ofthe screw head I8, and if the diameter of the anvil 82 were greater thanthat of the screw head I9, there would then be a vacancy between them,or a gap, at the point mandrel 46, against the walls of the aperture 42,

I position, the rim will be held so designed as to permit might then,owing to the small dimensions above described, result in the screw I2being forced downward to fill this vacancy or gap. Instead of thedesired, controlled expansion, there might be an uncontrolled upsettingaction of the threads.

An effective lock is thus provided against accidental loosening of thescrew-threaded members, both ends of which are exposed to view, andwithout'disfiguring the final product, for an article, like anophthalmic mounting, that is worn on the face, must have an attractiveappearance.

In Figs. 3 and 9, the end pieces 4 and 9 are shown attached to the splitlens rim 2 at a point above the center of the rim. When using the toolof the present invention to lock the screw I2 in upside down, asillustrated. The.tool is clear vision of the aperture 42 in thesorew I2,in order that the mandrel 49 may be inserted accurately into theaperture 42 without difliculty before the expanding pressure is applied.If the jaw 19 were shaped as in Fig. 8, therefore, it would not serve sowell for the type of lens rim illustrated in Figs. 3 and 9, having aportion 93 of the rim arching over the end piece 4.

According to the preferred embodiment of the present invention,therefore, the mandrel 49 is mounted upon a support 92 that is offsetfrom the mandrel 49, and that inclines somewhat sharply toward themandrel 49, providing an inclined face 94 adapted to be positionedadjacent to the said overarching portion 93 of the lens rim, so as notto interfere with the said over-arching portion 99 of the rim. Therelative dimensions and angle of incline are very important; for unlessthe inclined face 94 is exactly the right distance from the mandrel 49,it will not be possible conven- 'iently to locate the mandrel 49 in theaperture 42, as before described. The governing factor is the angle ofthe over-arching portion 99 of the lens rim 2.

The anvil 92 is similarly mounted upon a support 99 that is likewiseprovided with an inclined portion 99 between the body portion of the Isupport 99 and the anvil 92, but the angle of incline of the inclinedportion 99 need not be so carefully selected, as the portion I 99 of thelens rim that is adjacent to the end piece 9 leaves the said end piece 9at a widely obtuse angle.

The supports 92 and 99 are shown constituted of plate or sheet metal, soas to withstand the necessary strains without springing. The planes ofthe plate or sheet are substantially at right allel to the angles to theoppositely disposed faces I92 and I94 of the jaws I9 and 84 upon whichthey are supported. The faces I92 and I94 may be provided withlongitudinally disposed grooves I 99 and I99 in which the supports 92and 99 are adapted to rest. They may be held in position in the groovesI99 and I99 by studs H9 and H2. The studs may be round bolts, as shown.

The grooves I99 and I99 may extend throughout the length of the jaws, orthey may consist of separated openings or perforations H4, H9. H9 and I29 for receiving projections I22 and I24 upon the respective plates 92and 99.

It will be understood that the dimensions above given are forillustrative purposes, and that, in any particular case, they may bevaried to suit such particular case.

The tool of the present invention may, of course, be used elsewherelugs, and for other purposes than to hold the end pieces 4 and 9together. I

Further modifications will occur to persons skilled in the art, and allsuch are intended to be included within the scope of the appendedclaims.

stantially equal to the length of the threaded opening so as to form acontinuous, annular, exteriorly threaded wall throughout substantiallythe said length, the tool comprising two cooperating Jaws, a swagingmandrel carried by one of the jaws, the free end of the mandrel having across section small enough to permit the mandrel to enter the aperture,but the body of the mandrel being large enough to enable the mandrel,during its said entry into the aperture, to swage the continuous,annular wall by expansion, without breaking the continuity of theannular wall, into tight engagement with the wall of the threadedopening, throughout a distance substantially equal to the said length,the material and the dimensions of the screw being such as to cause theexterior threads upon the annular wall to lock frictionally against thethreads of the threaded opening throughout substantially the said lengthby the inherent resiliency of the swaged metal of the screw without theaid of a locking plug permanently positioned in the aperture, and ananvil carried by the other jaw for supporting the head of the screwduring the said entry of the mandrel into the aperture. i

2. An expanding tool for use with a split, ophthalmic-mounting. lens rimhaving end pieces of relatively light material at a point above thecenter of the rim, whereby a portion of,-.-the rim arches over one ofthe end pieces, the end pieces being adapted to be connected together bya relatively small-dimensioned, light, substantially cylindrical, metalscrew threaded into a threaded opening in one of the end pieces, and thescrew having an aperture extending substantially paraxis of the cylinderfrom its free end inward toward the head of the screw for a distancesubstantially equal to the length of the threaded opening so as to forma continuous, an-

nular, exteriorly threaded wall throughout substantlally the saidlength, the

tool comprising as shown in Fig. 6,

than in ophthalmic mounttwo cooperating'iaws, one of the jaws having asupport and a portion extending outward therefrom at a sharp incline soas to be bent away from the support, whereby the said sharply inclinedportion is adapted to be disposed adjacent to the said overarchingportion of the lens rim, a swaging mandrel carried by the said sharplyinclined, bent-away portion, the free end of the mandrel having a crosssection small enough to permit the mandrel to enter the aperture, butthe body of the mandrel being large enough to enable the mandrel, duringits said entry into the aperture, to swage the continuous, annular wallby expansion, without breaking the continuity of the annular wall, intotight engagement with-the wall of the threaded opening, throughout adistance substantially equalto the said length, the material and thedimensionsof the screw being such as to cause the exterior threads uponthe annu- ,lar wall to lock frictionally against the threads screwhaving an aperture extending substantially parallel to the axis of thecylinder from its free end inward toward the head of the screw for adistance substantially equal to the length of the threaded opening so asto form a continuous, annular, exteriorly threaded wall throughoutsubstantially the said length, the tool comprising two cooperating jaws,a plate support carried by each jaw, a swaging mandrel upon one of thesupports, the free end of the mandrel having a cross section smallenough to permit the mandrel to enter the aperture, but the body of themandrel being large enough to enable the mandrel during its saidentryinto the aperture, to swage the continuous, annular wall by expansion,without breaking the continuity of the annular wall, into mounting ofrelatively light material, and the tight engagement with the wall of thethreaded opening, throughout a distance substantially equal to the saidlength, the material and the dimensions of the screw being such as tocause the exterior threads upon the annular wall to lock frictionallyagainst the threads of the threaded opening throughout substantially thesaid length by the inherent resiliency of the swaged the mandrel intothe aperture.

FREDERICK A, STEVENS.

